PromptProviderConfig.java

package com.tutego.ch_02.configurationClasses;

import org.jline.utils.AttributedString;
import org.jline.utils.AttributedStyle;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.shell.jline.PromptProvider;

import java.util.UUID;

/*
* @Component relies on static graph resolution but some beans might require some more flexibility in terms of configuration.
* When using @Configuration Spring will create a proxy object to guarantee correctness (internally the proxy memoizes the bean method evaluations)
* Proxies can be disabled for easier native compilation, but it will only work correctly for decoupled beans (!!)
*/
@Configuration(proxyBeanMethods = false)
public class PromptProviderConfig {

    private static final PromptProvider USER_PROMPT_PROVIDER =
            () -> new AttributedString("date4u:>");

    private static final PromptProvider ADMIN_PROMPT_PROVIDER =
            () -> new AttributedString(
                    "date4u[admin]:>",
                    AttributedStyle.DEFAULT.foreground(AttributedStyle.RED)
            );

    @Bean // instantiated once at the beginning of the application, just like any other component
    public PromptProvider promptProvider(Environment env) {
        return env.containsProperty("admin") ? ADMIN_PROMPT_PROVIDER : USER_PROMPT_PROVIDER;
    }

    @Bean // instantiating several components of the same type isn't a problem, injection is.
    public UUID a() {
        return UUID.randomUUID();
    }

    @Bean
    public UUID b() {
        return UUID.randomUUID();
    }

}